Query language for Concord key-value store.
Provides pattern matching, range queries, and filtering capabilities for efficient data retrieval.
Features
- Pattern Matching: Find keys by prefix, suffix, contains, or regex
- Range Queries: Retrieve keys within a specific range
- Value Filtering: Filter results by value predicates
- Limit & Offset: Pagination support
- Sorted Results: Automatic key sorting
Examples
# Find all user keys
Concord.Query.keys(prefix: "user:")
# Find keys in range
Concord.Query.keys(range: {"user:100", "user:200"})
# Find keys matching pattern
Concord.Query.keys(pattern: ~r/user:\d+/)
# Get values with filtering
Concord.Query.where(prefix: "product:", filter: fn {_k, v} -> v.price > 100 end)
# Paginated results
Concord.Query.keys(prefix: "order:", limit: 50, offset: 100)Summary
Functions
Count keys matching the given criteria.
Delete all keys matching the given criteria.
Query keys matching the given criteria.
Query key-value pairs matching the given criteria.
Types
@type key() :: binary()
@type pattern() :: Regex.t()
@type query_opts() :: [ prefix: binary(), suffix: binary(), contains: binary(), pattern: pattern(), range: range(), limit: pos_integer(), offset: non_neg_integer() ]
@type value() :: term()
@type where_opts() :: [ filter: filter_fn(), limit: pos_integer(), offset: non_neg_integer(), prefix: binary(), suffix: binary(), contains: binary(), pattern: pattern(), range: range() ]
Functions
@spec count(query_opts()) :: {:ok, non_neg_integer()} | {:error, term()}
Count keys matching the given criteria.
Examples
Concord.Query.count(prefix: "user:")
# => {:ok, 1543}
Concord.Query.count(range: {"order:2024-01-01", "order:2024-12-31"})
# => {:ok, 8234}@spec delete_where(query_opts()) :: {:ok, non_neg_integer()} | {:error, term()}
Delete all keys matching the given criteria.
Returns the number of keys deleted.
Examples
# Delete all temporary keys
Concord.Query.delete_where(prefix: "temp:")
# => {:ok, 42}
# Delete old orders
Concord.Query.delete_where(range: {"order:2020-01-01", "order:2020-12-31"})
# => {:ok, 1543}@spec keys(query_opts()) :: {:ok, [key()]} | {:error, term()}
Query keys matching the given criteria.
Options
:prefix- Match keys starting with this string:suffix- Match keys ending with this string:contains- Match keys containing this string:pattern- Match keys against a regex pattern:range- Match keys in range{start_key, end_key}(inclusive):limit- Maximum number of results to return:offset- Number of results to skip
Examples
# Prefix matching
Concord.Query.keys(prefix: "user:")
# => ["user:1", "user:2", "user:123"]
# Range query
Concord.Query.keys(range: {"user:100", "user:200"})
# => ["user:100", "user:150", "user:200"]
# Regex pattern
Concord.Query.keys(pattern: ~r/user:\d{3}/)
# => ["user:100", "user:200", "user:999"]
# Pagination
Concord.Query.keys(prefix: "order:", limit: 50, offset: 100)
# => 50 keys starting from the 101st key@spec where(where_opts()) :: {:ok, [{key(), value()}]} | {:error, term()}
Query key-value pairs matching the given criteria.
Similar to keys/1 but returns both keys and values.
Options
Same as keys/1, plus:
:filter- A function({key, value} -> boolean())to filter results by value
Examples
# Get all user records
Concord.Query.where(prefix: "user:")
# => {:ok, [{"user:1", %{name: "Alice"}}, {"user:2", %{name: "Bob"}}]}
# Filter by value
Concord.Query.where(
prefix: "product:",
filter: fn {_k, v} -> v.price > 100 end
)
# => {:ok, [{"product:1", %{price: 150}}, {"product:2", %{price: 200}}]}
# Range with filtering
Concord.Query.where(
range: {"order:2024-01-01", "order:2024-12-31"},
filter: fn {_k, v} -> v.status == :completed end
)